{{ if isset .Params "categories" }}
{{ if not (eq (len .Params.categories) 0) }}
<span class="article-category"><i class="icon icon-folder"></i> 
  {{ range .Params.categories }}
  <a class="article-category-link" href="/categories/{{ . | urlize }}">{{ . }}</a>
  {{ end }}
</span>
{{ end }}
{{ end }}